Computer memory systems typically have a main or primary memory board and a plurality of secondary memory boards or memory components, for example dual in-line memory modules (DIMMs). The secondary memory boards are inserted into slots or connectors loaded onto the main or primary memory board. Typical memory subsystem implementations place all the connectors for the DIMMs and all the supporting components, such as buffer chips, on one side of the main memory board. Because the density in servers is increasing the available real estate for the memory subsystem is decreasing. Having all the connectors and components on one side of the main memory board limits the number of secondary boards that can be loaded onto a given sized main memory board.
DIMMs come in a number of different types. Some DIMMs use mainstream commodity DIMM technology. Other DIMMs use more expensive custom technologies. DIMMs that use the mainstream commodity DIMM technology are typically cheaper than DIMMs that use the custom technology. DIMMs that use the mainstream commodity DIMM technology typically require buffer chips to be loaded onto the main memory boards along with the DIMM connectors. DIMMs that use the custom technologies typically have buffer chips intergraded into the DIMM chips. Because the buffer chips are intergraded into the DIMMs the buffer chips are not required on the main memory boards and the DIMM connectors can be packed into a smaller volume.